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/* Copyright (C) 2000-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <not-cancel.h>
static int itc_usable;
static int
has_cpuclock (void)
{
if (__builtin_expect (itc_usable == 0, 0))
{
int newval = 1;
int fd = __open_nocancel ("/proc/sal/itc_drift", O_RDONLY);
if (__builtin_expect (fd != -1, 1))
{
char buf[16];
/* We expect the file to contain a single digit followed by
a newline. If the format changes we better not rely on
the file content. */
if (__read_nocancel (fd, buf, sizeof buf) != 2
|| buf[0] != '0' || buf[1] != '\n')
newval = -1;
__close_nocancel_nostatus (fd);
}
itc_usable = newval;
}
return itc_usable;
}
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